FJR brake issue

[Rickard]

Hello there,
I have a FJR 2006 with ABS brakes. Recently, after a period of approx. 1 month sitting in the garage, the rear brake pedal of the motorcycle started to feel... rubbery (for lack of a better word).
What I mean is that normally, when you push the brake pedal with an appropriate force, the pedal would stop on a defined point because of the oil brake pressure. Now what happens is that when I push the brake pedal, it will go all the way down as if there was no brake oil in the system, and the rear braking power seems somewhat weak.
I've checked brake oil and it was fine. I bled the ABS system according to the service manual with an appropriate brake oil but the problem persists.
Has any of you faced this kind of problem before? do you think the ABS module is faulty? or is it something else?

Thanks in advance.

 

[Geezer]

It sounds like you need to bleed the brakes.

 

[ionbeam]

Remembering that the front and rear brakes are linked. You have to bleed the front caliper and then the rear caliper. It's in the FSM.

 

[Niehart]

Also clean the shaft of the brake pedal first.

 

[Twigg]

It is probably as the others said ... bleed the brakes and replace all the old fluid with new.

If it is still a problem, and you are sure all the air is out of the system, then the likely culprit is the piston seal in the cylinder. The symptoms are very similar because as you press the pedal some of the fluid is escaping past the sea, reducing braking and increasing pedal travel.

 

[HotRodZilla]

One of two things: Either you didn't properly locate the rear fluid reservoir, which is under the seat and behind the right side silver panel

-or-

You didn't bleed the lower right front caliper, which is linked to the rear brake.

I say this because these issues are what 90% of people with rear brake problems seem to encounter.

 

[escapefjrtist]

Agree with all...make sure you're bleeding both right front and rear calipers.

Also clean the shaft of the brake pedal first.

Huh? I just give mine a small shot of grease...

--G

 

[Niehart]

Also clean the shaft of the brake pedal first.

Huh? I just give mine a small shot of grease...

--G

Show off.

 

[Rickard]

Thank you for the answers.
After encountering this issue, I thoroughly bled the brakes according to the service manual, where you have to bleed first the front brake calipers, then the right front brake caliper (from the unified brake system), and finally the rear brake caliper. I was careful not to let any air in the system.

Maybe I can try and bleed again, though.

One of two things: Either you didn't properly locate the rear fluid reservoir, which is under the seat and behind the right side silver panel

-or-

You didn't bleed the lower right front caliper, which is linked to the rear brake.

Yes, I bled the caliper corresponding to the linked rear brake and I'm positive I was filling the correct reservoirs.

If it is still a problem, and you are sure all the air is out of the system, then the likely culprit is the piston seal in the cylinder.

I was not very careful in this but I checked and there doesn't seem to be any leak on the piston. But I'll be sure to check the seal.

 

[Twigg]

Thank you for the answers.After encountering this issue, I thoroughly bled the brakes according to the service manual, where you have to bleed first the front brake calipers, then the right front brake caliper (from the unified brake system), and finally the rear brake caliper. I was careful not to let any air in the system.

Maybe I can try and bleed again, though.

I was not very careful in this but I checked and there doesn't seem to be any leak on the piston. But I'll be sure to check the seal.

It isn't easy to actually check the seal because when they start to leak it is often only when under high pressure. If you have ruled out everything else and it still doesn't firm up the brake, then change the seal, don't mess around trying to check it.

If you have the m/c apart, check the cylinder bore for wear or scoring.

 

[Geezer]

I know of 2 cases where the rear brake went soft and it required a very thorough bleeding to get it working again. I think if you bleed a second time it will help.

Before you do the next bleeding you should try to exercise the ABS in case there is air in the ABS components. I would think that a ride on a gravel road with hard but careful use of the rear brake would cause the ABS to kick in once or twice.

 

[BigOgre]

I know of 2 cases where the rear brake went soft and it required a very thorough bleeding to get it working again. I think if you bleed a second time it will help.

+1^ I've experienced this myself. I'll flush at least annually (Speedbleeders + ~$4 fluid = why not?). First time it went soft left me thinking about larger problems but now it just means a few more pumps and it's always firmed right up.

 

[900gc]

Normally just a couple of good bleeds do the trick unless there is some other hardware issue. FYI, if you search these topics on this site (or google; FJR forum, bla,bla,bla), you'll find a WEALTH of info and details from many threads with a TON of great advice about all things FJR.